What difference can she really make?
by IsabelleSharon
Summary: When John's sickly, younger sister, Katherine Watson moves into 221B Sherlock doesn't know exactly what to make of her. As she joins their group . What difference can a seemingly odd, young girl make in the heart in our lovely Holmes? And who is Abigail? Why does the name of her make the two Holmes brother go silent? I need 3 reviews before another chapter! 3 good reviews!


_**Hey everyone! So this is my first Sherlock fanfiction so please give me a chance. I am just going to make it clear that this may or may not continue based on interest of the first chapter. This starts in-between season 1 and 2. Like in all of my other fanfictions I am a learning writer and constructive criticism is necessary. This applies for the rest of this I do not own any TV or book just Katie Watson… I really wish I did own it or Moffat would write in my ideas… oh well we must go on to the show!**_

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"Where are you going?" Sherlock asked playing on his violin, staring out the window. John was putting his coat on "Your not going on another useless date are you? Especially dressed like that?"

"Going to pick my sister up? She's moving in remember?... What's wrong with the way I dress?"

"Harriet?" Sherlock asked confused,

"No, my younger sister. I told several times this week."

"No you didn't."

"_My little sister needs a place to stay, I don't want her living by herself. Would you mind if I asked her to move in the guest room."_

"_Whatever, can you pick up some milk when you get back?"_

_Later_

"_I talked to Mrs. Hudson, she said it would be fine. Thanks again, she's only 19 so make sure your nice."_

"_Sure, now be quiet I'm thinking."_

"You didn't say a thing."

"Well whatever, you have to be nice. She's not used to well… you. I don't want her offended or upset. If you act inappropriately I will not go on your next case." John warned.

"Fine, I will try to play nice." Sherlock said in a dull tone plucking cords on his violin.

Several minutes after John left, Sherlock heard the doorbell and he could hear Mrs. Hudson talking to someone.

"Uh, hello, I'm here to see Mr. Sherlock Holmes." The voice was that of a young woman, there was slight breathlessness to it. Mrs. Hudson walked the young woman upstairs.

"Just right in there pet."

"Thank you." The girl knocked on the door.

"Come in." The deep voice responded, the girl quietly entered the room as Sherlock examined her, _light, honey auburn hair, and large almond shaped, hazel eyes. Same structure of face… Relative of John's, younger sister most likely. Silver medical bracelet, small cough, pale, has been sick recently, and based on the bracelet probably part of some sort of long-term illness. Minor when it wants to be but can get bad from time to time. Needs looking after. _

"Hello, Mr. Holmes. I'm Katherine Watson but everyone calls me Katie. I'm John's…" She held out her hand, looking him strait in the eye, _Respectable person, definitely raised in John's household… no by John himself._

"Sherlock, just call me Sherlock. It is rather obvious you are John's younger sister." Sherlock shook the girls hand more to examine her then to be polite, _Short nails, works with hands, not too rough calluses, light worker, dent in middle finger on right hand, writer, most likely some kind of music composer._ "Sit" Sherlock demanded, she took a seat, examining the man with her hazel eyes. "Your brother went to pick you up." Sherlock informed her continuing to examine her.

"I know, but I wanted to come on my own. I wanted to meet you for myself first." She said, her tone even but a slight nervous playing with her blouse.

"Piano player?" Sherlock asked walking around the room, being in-between cases he unusually was intrigued by the young girl. _Sit's tall but still leans against the side of the chair, yes definitely tired from traveling._ "Mrs. Hudson made me put her old piano up here, I don't use it as I play violin. It's tuned… I can't stand unturned instruments, I would like to hear you play." Sherlock said with a forced smile, remembering what John had said about being nice.

"Thank you, but I don't think you would have an interest in my piano playing. Mr. Hol… Sherlock, you may be a very clever man but I still can tell if someone wants to listen to my playing or not. I know you have figured it out using logic but please could you humor me and tell me how you figured that all out?" The girl asked, revealing a little excitement in her voice.

"Your hands are that of a composer, a noticeable dent on your right hand on the middle finger from using a pencil to write, a writer uses a computer but a musician would use a pencil or pen. Your posture is that of a practiced musician. Your nails are short meaning you use your hands. How I found out piano specifically was more of a well-placed guess, as your medical bracelet would suggest you could be sickly meaning you wouldn't play an instrument that you would carry or hold. Most likely being a piano, as well you have been playing a song on your lap ever since you got here. Probably a nervous habit." Sherlock said, trying harder then every before to not offend someone. A case without John would be the worst in the entire world.

"Wow… brilliant… May I do my own deduction."

"Fine, I have nothing better to do."

"My brother probably told you to be nice. There wouldn't be a need for you to talk if you listened to me play. But I can tell you like to talk but out of all the people in the world John is probably the only person you would listen to in a case like this. You two are like brother's, he probably threatened you in some way in order to keep you in check." Katie said in a kind voice. "Don't worry about offending me. I wont be, I, like you, respect my brother immensely. You have helped a lot with his stress after the war. You gave him a purpose and I thank you for that. As long as you are his friend and helping him I promise I wont be scared away, but may I point out that if you hurt him there will be consequences. So what can you make of me?" Katie said with amusement in her eyes. Sherlock was expecting a little less, sure she didn't have her skill but she could see what he generally missed… The respect or emotions of others.

"Your in your early 20's, guessing from your clothes unemployed. You have an invisible illness that effect's your energy. Based on your stance you have spent a lot of time with John and have picked up some of his military conduct.

You dressed in a dress shirt but you are wearing jeans meaning you want to make a good impression but you aren't completely held by appearance. The little bit of make up you have came from a healthier time in your life as it is darker than the rest of your skin. John sent you those earing's last Christmas, you wear them everyday, while your necklace was your grandmother's she gave you to cope with something.

You were premature which are the main cause of your illness and also the reason of your birthmother's death. You may not be able to live by yourself but you are independent person. You are the youngest but you don't act like a baby of a family, probably had an event in your life that made you age. I already know your older sister drinks and you and she probably switched in your normal tendencies for birth order. The event was probably your father leaving perhaps, and your stepmother taking to drink?

You were top of your year at school but didn't have many friends. When everyone else was out and going to parties you stayed in and studied. You have been tossed around, going from family member to family member, you were last with your older step-sister when you got sick and she said that she couldn't handle taking care of you. You worry about your family but you also worry that you are a hindrance to them." Sherlock looked at her "How right am I?"

"It was my step-mother that left, I'm also 21 to be specific."

"Details missed." Katie couldn't help but laugh a little at his reaction. Yes he had said things that were hard for her to even admit to herself but it was her who asked, she was impressed. Sherlock gave her a confused look, very rarely did anyone laugh at him when he did that.

"I think we will get along well Sherlock…"

"Katie Jane!" John was breathless in the doorway "You were suppose to wait for me at the airport."

"Johnny, I sent you text didn't you see it?" Katie asked getting up suddenly.

"Yes, I got it as soon as I got to the airport." John examined his little sister, she was skinnier than the last time he saw her as well as paler. But he smiled at the thought of finally being able to know that she would be close to him, made him relax a bit. "Come here" John hugged his little sister

"Miss me much Johnny?" Katie asked laughing; Sherlock made a note of how small the girl really was. Being shorter than even John by a couple of inches which in his opinion was quite an accomplishment.

"Whatever, I'm just glad you're here. How are you feeling?"

"I'm fine, I'm getting better everyday. Sherlock and I were introducing ourselves to each other." John gave Sherlock a questioning look, "He was being a right gentleman. You trained him well."

"I wish… Well where are your things I'll show you to your room."

"Their downstairs, thanks so much. I will try to stay out of your hair. I'm going to work on testing out of the university."

"Don't worry about it! I'm just glad you are here."

"Are all siblings like this? I mean that aren't my brother and I?" Sherlock asked

"Ignore him, he's in-between cases." The two laughed lightly, leaving a disgruntled Sherlock alone. No woman, no person in that fact head read Sherlock like that. Knowing what he was thinking or the reason behind his actions. When he first heard of the girl he assumed another boring person but this one he figured was someone to look into.

Another thing that was odd was the relationship between the siblings. They were very close but not only in knowing each other's whereabouts but also compatible. John worried over the girl like an old man; from the looks of it John had truly been the one to raise her. As they talked Sherlock was first silent and reserved not really coming into the conversation.

"Sherlock, do you really shoot the wall when your bored."

"Yes, why?"

"I just think its kind of funny. From what John's told me about you; you are really an odd person. I am glad to find another odd soul." She smiled at him, it was rather odd, sure he had a few people smile at him, Molly almost always acted kindly toward him but this wasn't the Molly did. It was rather she was just trying to understand, definitely not something he was used too and he really didn't know how to react. "You know to thank you for letting me stay here I am going to make you boys some dinner." She got up to go look in the kitchen when John remembered the head…

"Katie! Don't open the fridge…" John sighed as his sister just did the opposite of what he told her. She let out a small scream.

"What is a head doing in the fridge?" She turned to the men.

"Experiment. I got it from the morgue."

"How about we just go out?" John suggested.

"I'm not going." Sherlock said returning to his brooding self, looking away.

"Yes you are!" Katie walked strait up to Sherlock.

"Katie you cant convince him…"

"I don't care John, it's my first time in a while to be back in London. Look here Mr. Holmes, I just got here, my last couple I have been all cooped up. I meet a man who is my brother's flat mate and I expect him to come with us to dinner. I also am guessing you haven't been out in a while so you need the air." John just stared at his little sister, sure she looked tired but there was a spark in her eyes that he hadn't seen in a long time. He watched as Sherlock had to stare down into his sister's honest eyes, there was a silent battle between the two bright people.

"Where do you wish to go?" Sherlock finally relented

"Wherever you think is the best place in town." She said smiling brightly, "Thank you! I better grab my umbrella from my bag, it looks like it might rain." Katherine grabbed her coat and ran out of the room. John just stared at his flatmate with wide eyes. Never once had he seen Sherlock loose on such a thing… or ever.

"Why didn't you tell me about her?" Sherlock finally asked

"I did mention her several times… what has gotten into you?" John asked

"I simply don't understand her, I can read her history like anyone else but her reactions are simply unpredictable. I don't know what to expect." Sherlock said pulling on his coat and turning up the collar of his jacket.

"Katie has always been that way, she lives by the idea that you may not be able to control your environment but you will be able to control reaction to it." John said grabbing his own coat. Going out to the entryway to see Mrs. Hudson and Katie chatting.

"Going out too Mrs. Hudson?" John asked seeing she was in a coat as well.

"The neighborhood ladies started a book club, and I decided to join. Now you two be gentleman and show Katie a good time." Mrs. Hudson reprimanded.

"Don't worry, I will make sure they do. Ready boys?" Katie held out her arms for both John and Sherlock to take. John naturally went to his sister's side but Sherlock looked at the young woman questioningly. "Don't worry I don't bite… most of the time." She smiled up at him as he slowly took it and they walked out the door. No one noticed those watching them as they made their way around London at night.

_**~What difference can she really make?~**_


End file.
